Kudo M, Niimi K
J Comp Neurol. 1980 Jun 15;191(4):545-56. doi: 10.1002/cne.901910403.
The ascending projections of the inferior colliculus (IC) in the cat were traced by the autoradiographic method, with special reference in the differenial projections of each subnucleus of IC. The laminated ventrolateral part of the central nucleus of IC (CNv) projects to the ventral and medial divisions of the ipsilateral medial geniculate body (MGB). The projections to the ventral division are topographically organized in the mediolateral direction, the terminals being arranged in the form of lamina, while those to the medial division are diffuse. The unlaminated dorsomedial part of the central nucleus of IC (CNd) sends fibers to every division of the ipsilateral MGB, particularly to the dorsal division and the ventromedial portion of the ventral division. It is noteworthy that the external nucleus of IC (EN) projects to the superior colliculus, part of the pretectum, and the anterior extremity of MGB ipsilaterally, in addition to the ventral and medial divisions of MGB. The posterior cap of IC, regarded as the pericentral nucleus of IC (PC), projects ipsilaterally to the ventral part of the caudal tip of MGB and the posterior part of the suprapeduncular nucleus. In addition of these projections, the parabrachial region and interstitial nucleus of the brachium of IC (BIC) are identified as common targets of projections of each nucleus of IC on the ipsilateral side. Contralaterally, every subnucleus of IC except for PC projects via the commissure of IC to areas corresponding to the targets of the ipsilateral projections, such as the ventral and medial divisions of MGB and the parabrachial region and the interstitial nucleus of BIC, although these contraleral projections are in general much sparser than those ipsilateral. Intrinsic and commissural connections within IC are also revealed in this study, providing characteristic configurations of each subnucleus of IC. It is concluded that the ascending projections of IC in the cat are highly differentially organized according to its subnucleus.
采用放射自显影法追踪了猫下丘（IC）的上行投射，特别关注了IC各亚核的差异投射。IC中央核（CN）分层的腹外侧部分投射到同侧内侧膝状体（MGB）的腹侧和内侧部分。到腹侧部分的投射在内外侧方向上呈拓扑组织，终末呈层状排列，而到内侧部分的投射则是弥散的。IC中央核未分层的背内侧部分（CNd）向同侧MGB的各个部分发送纤维，特别是背侧部分和腹侧部分的腹内侧部。值得注意的是，IC的外侧核（EN）除了投射到MGB的腹侧和内侧部分外，还同侧投射到上丘、顶盖前区的一部分以及MGB的前端。IC的后帽，被视为IC的中央周核（PC），同侧投射到MGB尾端的腹侧部分和上丘臂核的后部。除了这些投射外，臂旁区和IC臂间质核（BIC）被确定为IC各核同侧投射的共同靶点。对侧方面，除PC外，IC的每个亚核都通过IC连合投射到与同侧投射靶点相对应的区域，如MGB的腹侧和内侧部分、臂旁区以及BIC的间质核，尽管这些对侧投射通常比同侧投射稀疏得多。本研究还揭示了IC内的固有和连合连接，呈现出IC各亚核的特征性结构。得出的结论是，猫IC的上行投射根据其亚核高度分化组织。
